In a mobile network, a traffic having a high real-time characteristic such as Web browsing, video viewing, or communication is handled. Moreover, not only a traffic having a high real-time characteristic, but also various kinds of traffics such as a traffic having a low real-time characteristic including content downloading and application updating are equally handled in a mixed and undistinguished manner. Thus, there has been a problem that communication quality of all traffics deteriorates when a peak load is generated.
There is an off-peak data transfer technique of transferring a traffic having a low real-time characteristic such as content downloading by utilizing an available bandwidth of a wireless link. The off-peak data transfer technique makes it possible to equalize a peak load in a wireless link without deteriorating communication quality of a traffic having a high real-time characteristic such as Web browsing.
The off-peak data transfer technique has an issue of how precisely an available bandwidth (a currently available bandwidth, e.g., a value represented by bit/s) in a wireless link is estimated.
Furthermore, in a mobile network, in order to improve communication quality of a wireless link and maintain sufficient communication service quality, a network operator needs to investigate communication quality in a communication area, adjusts various parameters, and thereby improve the communication quality. Herein, communication quality refers to, for example, an available bandwidth of a wireless link, or the like.
Regarding a technique of estimating an available bandwidth, for example, NPL 1 discloses a method of sending out a measurement packet called a probe to a measurement target network, and, by use of information (such as one-way transfer delay time) thereby obtained, estimating an available bandwidth.